Foam has long been recognized as a useful substance, particularly in the textile industry. Foam can be applied to a wide variety of textile materials for a wide variety of purposes. Exemplary of such applications is the application of a layer of foam to the underside of a carpet to provide an integral cushion therewith. Such layers can be relatively thick, as is often desirable in carpet applications, or relatively thin, as in the case of drapery fabrics and shoe insoles. Cushioning type foams can be made of natural rubber latex, synthetic rubber latex, blends thereof as well as a wide variety of other synthetic polymers which are well known in the art.
Foams also find applications in the area of dyeing and treatment of fabrics with resins, such as water repellants, fire retardants, so-called permanent press resins and the like. By replacing a portion of the liquid material with an air bubble to provide a foam, drying or curing time is reduced thereby conserving energy.
Essentially, the only requirement for a material to be foamable is that the material have appropriate surface properties in order to maintain a bubble or cellular structure for the desired period of time. Materials which are not otherwise foamable can usually be rendered foamable by the addition of a surface active agent. Such agents are well known in the art.
As used herein the term "foam" is intended to denote and mean a mixture of liquid and air, the air having been mechanically combined with the liquid as opposed to being chemically generated in situ. The term "froth" is sometimes applied to such mixtures of liquid and air and it is intended that the term foam includes the term froth.
For many applications, it is often desirable to produce foam in a continuous process, rather than in a batch process. Continuous foam homogenizers are well known in the art.
Typically, a continuous foam homogenizer produces foam by combining air with a foamable material and injecting the mixture under pressure into a homogenizing head where it is mixed, foamed and rendered a uniform density by a rotor turning at high speed within a stator. The rotor usually has a plurality of pins extending radially outward and the stator has a plurality of pins extending radially inward to enhance the mixing action of the spinning rotor. An example of such a foam homogenizer is shown in U.S. patent application Ser. No. 244,766 filed Mar. 17, 1981, now abandoned. These types of mechanical foam generators or foam homogenizers utilize a number of moving parts which are subject to wear and mechanical failure. Furthermore, the motor required to operate the homogenizer consumes a substantial amount of energy.